Contains the total number of bits in the color buffer of the /current
window's/ current layer. For an RGBA layer, this is the sum of the red,
green, blue, and alpha bits. For an color index layer, this is the number
of bits of the color indexes.

Contains the window system dependent format ID for the current layer of the
current window. On X11 GLUT implementations, this is the X visual ID. On
Win32 GLUT implementations, this is the Win32 Pixel Format Descriptor number.
This value is returned for debugging, benchmarking, and testing ease.

Vertex attribute state

(freeglut only) If vertexAttribCoord3 and vertexAttribNormal both
contain Nothing, the fixed function pipeline is used to draw
objects. Otherwise VBOs are used and the coordinates are passed via Just
this attribute location (for a vec3).

Layer state

Contains True if the given plane of the current window has been
damaged (by window system activity) since the last display callback was
triggered. Calling postRedisplay or
postOverlayRedisplay will not set this True.